The inventive concepts described herein relate to a semiconductor memory device, and more particularly, relate to a nonvolatile memory including a three-dimensional memory cell array.
A semiconductor memory device is a memory device which is fabricated using semiconductors such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), and the like. Semiconductor memory devices are classified into volatile memory devices and nonvolatile memory devices.
Volatile memory devices may lose stored contents when the power to the device is cut-off. Example volatile memory devices include static Random Access Memory (RAM) devices (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), and the like. Nonvolatile memory devices may retain stored contents even when power to the device is cut-off. Example nonvolatile memory devices include read only memory (ROM) devices, programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable and programmable ROM (EEPROM), flash memory devices, phase-change RAM (PRAM), magnetic RAM (MRAM), resistive RAM (RRAM), ferroelectric RAM (FRAM), and the like. Flash memory devices include both NOR type and NAND type flash memory devices.
In recent years, research on three-dimensional semiconductor memory devices has been conducted in an effort to obtain semiconductor memory devices having a higher degree of integration.